Feature request from ezequielalba, posted on GitHub Jan 19, 2016
I'm getting this issue after run grunt exec:<theme>, this shows up:
Processed Area: frontend, Locale: en_US, Theme: Ids/prueba, File type: less.
>> [Magento\Framework\Exception\FileSystemException]                                                                                                                                                                
>>   Cannot create a symlink for "/usr/local/devs/magento2/htdocs/vendor/magento/theme-frontend-blank/web/css/source/_reset.less" and place it to "/usr/local/devs/magento2/htdocs/pub/static/frontend/Ids/prueba/en_US/css/source/_reset.less" Warning!file_get_contents(/usr/local/devs/magento2/htdocs/var/cache//mage-tags/mage---e39_INTERCEPTION): failed to open stream: No such file or directory  
>> dev:source-theme:deploy [--type="..."] [--locale="..."] [--area="..."] [--theme="..."] [file1] ... [fileN]
>> Exited with code: 1.
Warning: Task "exec:prueba" failed. Use --force to continue.
And after i run grunt refresh, shows the same after it cleans all the paths.
Now, running the command for the bin/magento dev:source-theme:deploy got this:
Processed Area: frontend, Locale: en_US, Theme: Magento/luma, File type: less.
  [Magento\Framework\Exception\FileSystemException]                                                                                                                   
  Cannot create a symlink for "/usr/local/devs/magento2/htdocs/vendor/magento/theme-frontend-blank/web/css/source/_reset.less" and place it to "/usr/local/devs/mage  
  nto2/htdocs/pub/static/frontend/Magento/luma/en_US/css/source/_reset.less"                                                                                          
dev:source-theme:deploy [--type="..."] [--locale="..."] [--area="..."] [--theme="..."] [file1] ... [fileN]
I was triyng to fix this by following a lot of instructions on other issues already, nothing worked. 
Any ideas why this might be happening?
I have a VM configured running of Ubuntu 14.04.3 LTS , and have node 5.4.1 with npm 3.3.12
Update of the issue: If a run the bin/magento static:deploy and after that i run grunt less:theme it gives no errors, but when watching isnt detecting the changes in the .less files of the theme.